<Situation of Power Supply in Recent Passenger Vehicle>
The current mainstream voltage of the power transmitted through a power transmission line of a vehicle is 14 V in the case of a usual passenger vehicle, and 14×2=28 V in the case of a heavy vehicle such as a bus or a truck. In passenger vehicles, particularly, a power supply system which supplies power at a voltage which is higher than a conventional one, such as 42 V has begun to be employed because of demands for improving the efficiency of driving the load, and for driving at an efficiency which is optimum for respective loads.
In a power transmission line, therefore, an electric junction box (for example, a fuse block) in which many fuses are disposed in a pluggable/unpluggable manner, or mini fuses are used in order to protect electric circuits of various electrical components.
<Conventional Blade-Type Fuse 100>
As a conventional blade-type fuse which is to be used in an electric junction box or a mini fuse, a blade-type fuse 100 is shown in FIG. 11 (see Patent Literatures 1 and 2).
The blade-type fuse 100 exemplarily shown in FIG. 11 is a low-height type fuse in which the flattened fuse body 400 is held between two upper and lower insulating casings 200, 300 consisting of front and back sides, respectively.
<Fuse Body 400>
In the fuse body 400, a fusible portion 420 is disposed so as to lay across the facing inner edges of a pair of flat terminal portions 410, 410 which have a substantially rectangular shape, and which are parallel to each other. Through-holes 400K, 400K are formed in the upper and lower sides of each of the flat terminal portions 410, respectively.
<Upper and Lower Casings 200, 300>
Each of the upper and lower casings 200, 300 has a T-like shape as a whole as indicated by the hatching showing a transparent resin in FIG. 11. The casings are paired in the front and back side, and used while being coupled to each other.
Through-holes 200K are formed in one of the upper and lower casings (for example, the upper casing 200), and fixing posts 300K are formed in the other casing (for example, the lower casing 300), and the fuse body 400 is interposed between the casings. The fixing posts 300K of the lower casing 30 are passed through the through-holes 400K of the fuse body 400 to be fitted into the through-holes 200K of the upper casing 200, so that the upper and lower casings 200, 300 house the fuse body 400.
<Use of Blade-Type Fuse 100 in Electric Junction Box or Mini Fuse>
When the lower end side of the blade-type fuse 100 is housed in a housing portion in an electric junction box, the flat terminal portions 410, 410 which are in the ends of the fuse are inserted into two female terminals existing in the housing portion to be electrically connected to each other, respectively.
When the lower end side of the blade-type fuse 100 is inserted into a mini fuse, the flat terminal portions 410, 410 which are in the ends of the fuse are inserted into two bifurcated terminals disposed in the mini fuse to be electrically connected to each other, respectively. FIGS. 12(A) and 12(B) are perspective views showing a state where the conventional blade-type fuse 100 are inserted into two bifurcated terminals, FIG. 12(A) is a perspective view showing a state before the insertion into the bifurcated terminals, and FIG. 12(B) is a perspective view showing a state after the insertion.
In FIGS. 12(A) and 12(B), tapered parts of the lower ends of the flat terminal portions 410 of the blade-type fuse 100 are inserted into inlet openings 50E of the bifurcated terminals 50, and lowered in the direction as indicated by the white arrow. Then, thick parts of the flat terminal portions 410 push and expand bifurcated tip parts 50R and 50L of the bifurcated terminals 50 in directions of separating from each other, and finally stop. As a result, the blade-type fuse 100 and the bifurcated terminals 50 are electrically connected to each other as shown in FIG. 12(B). The position where the fitting stops is usually restricted by cavities.
The upper end side of the blade-type fuse 100 is swollen by a molding resin in the thickness and width directions the flat terminal portions 410. Therefore, in the case of replacing a fuse, for example, a worker can easily pull out the fuse from the terminals by nipping a swollen part 200T (see FIG. 11).